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#31
Re: why go twin instead of a single turbo u ask
L18_B110
Posted on: 2004/2/24 4:39
OK, lets go back to the first post:
Quote: Take a look at any factory-produced high-horsepower turbocar and you'll see there's always more than one turbo under the lid them's horse-apples. Could you make a more sweeping generalisation? I could give you a list a mile long of "factory-produced high-horsepower turbocars" with single turbo setups, but there aint any factory twin simultaneous turbo fours. If they are going to discuss the merits of twin turbo systems vs single, they really should specify what engine configurations they are referring to, and what type of twin turbo system they are referring to. Quote: or is your argument that you don't think it applies to 4cyl motors?, "show me any production car that has less than 3cyl feeding each turbo..." or maybe this one: "try thinking about why it is that there are no production 4cyl cars with this setup... " perhaps this one gave a bit of a clue: "The argument does not apply to 4cyl cars" Quote: i really don't understand that argument as i dont see why a 4cyl is any diffrent to a 6cyl or 8cyl, the TT GTR sklines are setup like i have mine, what's the diffrence if it's fed by 2 or 3 cylinders each???, i mean if you scale them to the same size, the 4cyl fires more often and fires more gas every time it fires, what's wrong with that? let me get this straight RC, you think a 4cyl engines fires more often than a 6? why is the frequency of cylinder firing important? so you always have exhaust flow working on the turbine wheel. That's what makes the whole show work after all... Why don't you see triple turbos on 6cyl? You've fallen for the age old "if some is good, more must be better" trap... Quote: theres 2 reasons i dont like speaking to places like Ray Hall or whoever, 1. being they are selling products and therefore are ALWAYS biased, 2. they don't understand the word BUDGET  
#32
Re: why go twin instead of a single turbo u ask
MadTimo
Posted on: 2004/2/24 4:51
Quote:
Not trying to go against the tt idea, I reckon its an awesome idea and will make a sweet car.....but I'm pretty sure you can get these times with twin or single turbo. Just maybe a bit more satisfaction out of getting the twin turbo one doing it.  But that aside, have you ever considered a laggy system to actually be an advantage?? If you think about it, isn't it nice to have a car that can putt around the streets like a normal 4 cylinder, being economical on fuel and tyres and keeping you out of trouble most of the time, but all thats needed to turn it into a fun, wheelspinning monster is a quick gear change.... And it can also be an advantage on launches. The best way to launch my 13B (with very large laggy turbo) was to drop the clutch just below boost and then let it come on boost. Using this system I was wasting heavily worked WRX's and fully tubbed V8's off the line using only 205 street tyres and well set-up suspension...true story.
#33
Re: why go twin instead of a single turbo u ask
B120dat
Posted on: 2004/2/24 6:19
twinturbo setup have lower boost threshold but it will also have reduced peak power, right?
wont the only thing that will give you better acceleration is more boost. so if you have a twin setup that makes more overall boost than a single you'll have more power? what advantage would a parallel twin turbo setup have over a larger single turbo creating the same or more boost. Lag? a twin setup must have lag issuses too.. wouldnt a sequential twin turbo setup be best with the smaller turbo spooling early and the larger kicking in later...... some food for thought, just what i was thinking bout the forum 
#34
Re: why go twin instead of a single turbo u ask
phunkdoktaspok
Posted on: 2004/2/24 12:28
Quote:
As far as I know, the twin turbo legacy is a sequential system, meaning all four cylinders drive each turbo, at different parts of the rev/load map. Ultimately this is the ideal setup, with limited lag from the smaller turbo but still having the top end power of a larger turbo. 1200RC's setup isn't sequential. It uses 2 cyl to fire one turbo and the other 2 cyl to fire the other turbo. 1200rc your newer design of cyl's 1 and 4 firing turbo 1 and cyl's 3 and 2 firing turbo 2 is better than the previous setup of cyl's 1 and 2 firing turbo 1 and cyl's 3 and 4 firing turbo 2. As the newer design evenly pulses the turbos throughout the engines cycle. Quote: it's true what it says, i remember my bro's starion (a little old skool but still) it would make positive boost at 80km/h in second gear, this meant he never really used boost, cause when it arrived he was already on the speed limit, basically in the every day driving around suburban roads it was pointless, the only time he could really use it was down the occasional freeway on ramp You can't compare these to setups. If you were to swap your 2 turbos for 1 turbo that had the same flow rates as the 2 turbos put together you would still get the same driving charactoristics from the single turbo as you did with the 2 turbos. Quote: The argument does not apply to 4cyl cars. A turbo works by the turbine being driven by exhaust gasses - obviously enough. But when you halve the number of cylinders feeding each turbo, you not only halve the total flow over the turbine, you have also made it operate on the turbine for half the time. Not big problem if you started with a 6cyl, but not so good if it was a 4cyl. Ever heard a V twin bike running? Nice way to drive a gas turbine huh? L18 I cant see how it doesnt apply to 4 cyl's. Yes as you say obviously a turbos turbine is driven off exhaust gases but when sized correctly 6, 4, 3 or 2 cyl's plays no part. I understand what you are sayin with the V twin bike engine but this cant compare to a turbo. On an engine the firing position is fixed ie; V twin #1 cyl fires at 0 degrees and #2 cyl fires at 180 degrees. So obviously if you ad more firing positions evenly the engine will rotate smoother. On a turbo there is no fixed exhaust pulsing position as the turbine is driven by gas flow. On an engine the exhaust gas flow for each cylinder pulse is varied through out different opperating conditions. So really 3 cyl's or 2 cyl's doesnt come into play. At the ended of the day it comes down to the turbos sizing for flow rates through the turbine housing. Quote: You've fallen for the age old "if some is good, more must be better" trap... As for that statement yeah I too belive thats true of 1200rc but L18 I think you yourself with your statements of there being no factory 4 cyl's with twin turbo setups means you have fallen into the way of thinking " Ive never seen anyone do it, so it must be impossible" Thats Just My Thoughts On The Subject. feel free to correct me if you think otherwise. Cheers Steve
#35
Re: why go twin instead of a single turbo u ask
ca18det_man
Posted on: 2004/2/24 12:40
Hi guys In my opinion you should just whack one of these on the side
 migth have a little bit of lag but will go pretty well on a 1200cc engine. LOL if your really game try two with 30psi. The stock bottom end should handle it you may need to run premium unleaded.Nice Turbo for A seriesCheers Andrew
#36
Re: why go twin instead of a single turbo u ask
Dodgeman
Posted on: 2004/2/24 12:52
Quote:
I think we will find that... A 45 degree V twin [Harley] with a single crankpin fires the front cyl, the crank rotates 315 degrees & fires the back cyl, rotates 405 degrees, fires [front] & continues at 315, then 405 degree intervals. A 90 degree V twin [Ducatti] with single crankpin, fires at 270 & 450 degree intervals The 90 degree design gives perfect primary balance with no rocking couple,... but they vibrate anyway.
#37
Re: why go twin instead of a single turbo u ask
phunkdoktaspok
Posted on: 2004/2/24 13:24
Ok Dodgeman I cant argue as I truely dont know but I do belive you.
But I am sure my point can be seen that on an engine the firing positions are fixed and this can't be compared to a turbos turbine and exhaust pulses.
#38
Re: why go twin instead of a single turbo u ask
Dodgeman
Posted on: 2004/2/24 13:30
Quote:
I accepted your invitation, & i thank you for the opportunity. I have not offered up any dissagreement with the thrust of the argument in your post.
#39
Re: why go twin instead of a single turbo u ask
phunkdoktaspok
Posted on: 2004/2/24 13:37
Like I said " I do belive you"
Quote: I accepted your invitation I would have been shocked if you hadn't corrected a fault. Cheers Steve
#40
Re: why go twin instead of a single turbo u ask
Dodgeman
Posted on: 2004/2/24 13:43
Interestingly enough, the Moto Morini motorcycle company in Bologna developed a turbo prototype 500cc V twin in the late 70's [I think it was the 500, could have been the 350] This was a 72 degree V twin & it went well enough, but it had too many other problems [air cooling] & did not go into production.
I had three of 1976 model, 350 Sport models from the Sept '76 shipment. There were only ten of these in the shipment & were known as the 3-1/2. Great bike. I still have a spare engine out of a wrecked bike from the February '76 shipment [10 bikes again] There were 2 shipments per year. Steve No one is questioning your belief. Please try not to be so sensitive The commentary was offered for the benefit of ALL who read this post & was not intended as a personal swipe. You can believe that too. If one minor technical detail is the worst mistake we make in our lives, then we have no problems. We couldn't have you in a state of shock,... could we?
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